TITLE:
Unsaponifiable Matter in Carnuba (Cera carnuba) Wax, a Modification of the USP/NF and FCC Methods
AUTHORS:
Yusuf Yildiz, Manjista Dasgupta
KEYWORDS:
Carnuba (Cera carnuba) Wax, Unsaponifiable Matter, Fatty Acids
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.7 No.8,
August
3,
2016
ABSTRACT: Carnuba wax
consists chiefly of myricyl cerotate (MW 817.4) and small quantities
of free cerotic acid (C26H52O2, Mw 396.7) and
myricyl alcohol (C30H62O, mp 90°C). Of the two common
extraction solvents, ethyl ether or petroleum ether, Lewkowitsch prefers the
former. Concerning separation of phases, he advocates addition of small amounts
of alcohol or caustic, and he also states that formation of a flocculant layer
between the aqueous layer and the solvent does not interfere with the correct
estimation of the unsaponifiable matter. These statements were not corroborated
in the hands of this chemist. The “Unsaponifiable Matter” in oils or and fats,
which consist mainly of hydrocarbons, sterols and aliphatic alcohols of high
molecular mass that are not saponifiable by alkali hydroxides but are soluble
in the ordinary fat solvents, and to products of saponification that are
soluble in such solvents. Carnuba wax, a rather expensive wax, may be
adulterated with less expensive paraffin by dishonest merchants. ASTM has a
method for determining paraffinic material in carnuba wax. It uses heptanes at
its boiling point to dissolve the wax, apply it to a silica gel column, and
elute only the nonpolar (i.e. alkane)
material. The method has the disadvantage of using a large volume of haptane,
nor is it called for by either US Pharmacopeia/National Formulary (USP/NF) or Food
Chemicals Codex (FCC). The test for unsaponifiable matter on pure carnuba wax
will yield a result of 50.0% - 55.0%, while a higher result will betray the presence
of paraffin adulterants.